1. Field of the Invention
The present invention relates to a microscope for observing microorganisms in water. More particularly, the present invention relates to an underwater microscope which can obtain a sharp picture of live underwater microorganisms in motion.
2. Description of Related Art
When researchers wanted to examine underwater microorganisms such as plankton or the like, conventionally, they drew up a water sample on board and carried it to a microscope prepared on board or on the ground and then dropped it on a preparation with sandwiched by cover glasses to observe the underwater microorganisms with an ordinary optical microscope. Especially, when many samples were needed, such as when there were many places to be researched or when a research was required per submerged depth of water, it took not only time and effort in picking up water samples, but also there was a problem with difficulties in securing a place for storing the water samples, or the like. Since underwater microorganisms had been dead by the time when they were observed after being sampled, it was very difficult to observe live underwater microorganisms in motion.
To solve this problem, a submersible microscope, with which researchers can directly observe underwater microorganisms, has been provided (Japanese Patent Application No.3-43916). That is, a camera and a luminous part are equipped within a watertight case, and a channel connecting to inside and outside the watertight case is placed near a focus of the camera. According to the underwater microscope in the present invention, direct observations of microorganisms in water, which eliminate the need for water samples, allow effects such as the prevention of deterioration with time, etc. to be confirmed. However, the following problems have been newly raised. One is that the picture becomes poor in sharpness due to the shake of the underwater microscope caused by ocean waves or the like. The other is that when studying the difference of microorganisms by the depth of water, latency becomes longer because of late interchange of water samples within the channel, which requires a long time for research.
In order to solve these problems, inventors of the present invention previously provided a submersible microscope, which quickly interchanged a water sample by connecting a pump to a channel and decreased the shake of the water sample within the channel by disposing a drain valve (Japanese Patent Application No.7-213314). In the underwater microscope of the present invention, there were still some problems left, regardless of the nearly sure attainment of its serviceable level by confirming prominent effects such as the speedy interchange of the water sample within the channel and the sharp decrease in the shake of the water sample, or the like.
More specifically, when we try to observe live underwater microorganisms in motion as we can see in natural environments, we have to relatively widen and thicken a sample chamber located near a focus of an underwater microscope. However, the following problems have been raised:
1) Brightened whole image is caused by refraction of light due to the water sample, which leads to a lower contrast. PA1 2) A shake of the underwater microscope is caused by a large motion of the water sample within the sample chamber, which leads to a poor sharpness of the picture. PA1 3) Underwater microorganisms in brisk motion may go out of the field of view. PA1 4) It is difficult to observe underwater microorganisms in brisk motion while focusing.
For a method for observing live underwater microorganisms in motion, it is also possible to observe a picture transmitted from a camera on the boat with a microscope placed underwater while being towed by a boat. In this method, it was very difficult to obtain a sharp picture which clearly captured underwater microorganisms because the underwater microscope was terribly shaken by the movement of the boat and researchers observed them under a condition that there was a fairly swift flow of water near a focus of the microscope.